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-ray analysisKinoshita, Norikazu*; Noto, Takuma*; Nakajima, Hitoshi*; Kosako, Kazuaki*; Kato, Takahiro*; Kuroiwa, Yoichi*; Kurabe, Misako*; Sasaki, Yuki*; Torii, Kazuyuki*; Maeda, Makoto; et al.
Journal of Radioanalytical and Nuclear Chemistry, 332(2), p.479 - 486, 2023/02
Times Cited Count：0 Percentile：0.01(Chemistry, Analytical)Hanaki, Shotaro; Kinoshita, Takuma*; Kishimoto, Yasufumi*; Hayashi, Hirokazu
no journal, ,
The decommissioning of the "Monju" facility, a 30-year process, is divided into 4 phases. In Phase 1, spent fuel is transferred to a storage pool, while Phase 2 involves dismantling uncontaminated areas. Phase 3 focuses on dismantling sodium equipment. Ongoing evaluations in Phase 1 and 2 aim to identify radioactive materials in the facility, reduce worker and public exposure, and establish demolition methods. The assessment is categorized into activation contamination from structural material activation and secondary contamination from corrosion products produced by leaching. This summary provides an overview of the contamination distribution assessment and the activation contamination assessment for fuel handling equipment specific to sodium-cooled fast reactors (SFRs).
Kinoshita, Takuma*; Kishimoto, Yasufumi*; Hanaki, Shotaro; Hayashi, Hirokazu
no journal, ,
Dismantling in radiation-controlled area is planned in phase 3 of the "Monju" decommissioning program, but an assessment of contamination of the facilities is essential before starting the dismantling. The under-floor transfer car for fuel handling unique to "Monju" transports, undergoes gas replacement and preheats fuel assemblies. Due to neutrons generated from fuel, the structural materials are activated. The radioactivity of the car was assessed using the same methodology as the reactor's evaluation. The neutron flux distribution and activation levels were evaluated using a 2D RZ system, and a 3D analysis was conducted for validation. Additionally, it was confirmed that the activity of activation products is at most at L3 levels, and in most areas, it is below the clearance levels.
Kishimoto, Yasufumi*; Kinoshita, Takuma*; Hanaki, Shotaro; Hayashi, Hirokazu
no journal, ,
Dismantling in the radiation-controlled area is planned in phase 3 of the "Monju" decommissioning program, but an assessment of contamination of the facilities is essential before starting the dismantling. The unique Ex-Vessel Storage Tank (EVST) unique to "Monju" stores fuel in liquid sodium at 200 
C. It requires an evaluation of radioactivity due to neutron-induced structural material activation. The neutron flux distribution and radioactivity of the EVST were assessed by calculation using a 2D RZ system, validating the results through comparison with a 3D system. The assessment confirms that the maximum concentration of activity of activation product in the EVST structural material is at L3 level and generally below clearance level in most areas.
